stage2: support anon init through error unions and optionals

[Vexu]

No idea if this actually works since I can't get LLVM to work with stage2. Keep forgetting I can use stage1 with -fno-stage1.

[andrewrk]

What error do you get from ./zig build -Denable-llvm ?

[Vexu]

zig build -Denable-llvm gives:

ld.lld: error: undefined symbol: __libc_single_threaded
>>> referenced by atomicity.h:52 (/usr/include/c++/11.2.0/ext/atomicity.h:52)
>>>               zig_llvm.cpp.o:(std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release()) in archive /home/vexu/Documents/zig/zig/build/zigcpp/libzigcpp.a
>>> referenced by atomicity.h:52 (/usr/include/c++/11.2.0/ext/atomicity.h:52)
>>>               zig_llvm.cpp.o:(std::_Sp_counted_base<(__gnu_cxx::_Lock_policy)2>::_M_release()) in archive /home/vexu/Documents/zig/zig/build/zigcpp/libzigcpp.a
>>> referenced by cow-string-inst.o:(std::basic_string<char, std::char_traits<char>, std::allocator<char> >::~basic_string()) in archive /usr/lib/libstdc++.a
>>> referenced 342 more times

zig build -Dstatic-llvm -Duse-zig-libcxx --search-prefix ../zig-bootstrap/out/host gives thousands of undefined symbol errors which suggests that I'm using the wrong compiler somewhere.

[andrewrk]

What distro is this?

[Vexu]

Arch linux.

[Vexu]

$ cat a.c
extern char __libc_single_threaded;
int main(void) {
    return __libc_single_threaded;
}
$ clang a.c && ./a.out
$ zig run a.c -lc
ld.lld: error: undefined symbol: __libc_single_threaded
>>> referenced by a.c:3
>>>               /home/vexu/.cache/zig/o/beaf2795fe77dc6e0678cf2f5db03da6/a.o:(main)
thread 15567 panic: attempt to unwrap error: LLDReportedFailure
???:?:?: 0x55e25e3e6556 in ??? (???)
???:?:?: 0x55e25e3e6790 in ??? (???)
^C

Likely relevant.

[Vexu]

Fixed by:

diff --git a/build.zig b/build.zig
index 5896ab1a8..fb821ccf4 100644
--- a/build.zig
+++ b/build.zig
@@ -550,6 +550,7 @@ fn addCmakeCfgOptionsToExe(
                 else => |e| return e,
             };
             exe.linkSystemLibrary("unwind");
+            exe.linkSystemLibrary("c_nonshared");
         } else if (exe.target.isFreeBSD()) {
             try addCxxKnownPath(b, cfg, exe, "libc++.a", null, need_cpp_includes);
             exe.linkSystemLibrary("pthread");